Hair analysis as a non-invasive method for assessing the exposure of wildlife to per- and poly-fluoroalkyl substances (PFAS)

In mammals, exposure to PFAS is usually assessed by measuring burdens in internal organs (i.e., liver and brain) or plasma, while less emphasis is devoted to non-invasive and non-destructive methods. We assess the suitability of hair as a non-invasive matrix for monitoring the exposure of mammals to 33 PFAS, including perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs), perfluoroalkylether carboxylic acids (PFECAs), perfluoroalkylether sulfonic acids (PFESAs), perfluoroalkane sulfonyl fluoride-based substances (PASFs), and fluorotelomers (FTs). The Red fox is chosen as the target species due to its apical position in the terrestrial food web of the study area, the Cavallino-Treporti peninsula in North-East Italy. All analysed samples (n = 24) are positive for PFAS, with eight compounds quantified in all samples, including PFHxA, PFOA, PFDA, PFUnDA, PFDoDA, PFTriDA, PFTeDA, and PFOS. The highest mean concentration in hair samples is measured for PFOS (1.40 ± 0.48 ng g⁻¹ dw) followed by PFDoDA (0.31 ± 0.05 ng g⁻¹ dw), and PFOA (0.31 ± 0.19 ng g⁻¹ dw), while the mean ∑₃₃PFAS was 3.41 ± 0.93 ng g⁻¹ dw. The dominance of PFOS and long-chain PFAS in the PFAS profile and the occurrence of compounds with even-numbered carbon chains at higher concentrations than the odd-numbered compounds with a one-carbon longer chain (i.e., PFOA > PFNA, PFDA > PFUnDA, PFDoDA > PFTriDA) suggest the trophic transfer along the terrestrial food web as the primary exposure pathway in the study area. The data suggest hair analysis as a reliable, non-invasive method for assessing the possible exposure of mammals to PFAS and suggested that the Red fox can be used as a sentinel of the environment, embracing the One Health perspective.